JP4293734B2 - Electric power steering control device - Google Patents

Description

但し、Ｄ（ｓ）は次式で表される。
【数２】

ここで、
ｍ：車両重量
Ｉ：車両重心を通るｚ軸回りの慣性モーメント
Ｌ：ホイールベース（ｌ＝ｌｆ＋ｌｒ）
ｌｆ、ｌｒ：前、後車軸から重心までの水平距離
Ｆｆ、Ｆｒ：前、後輪タイヤのコーナリングフォース
Ｋｆ、Ｋｒ：前、後輪タイヤのコーナリングパワー
ｎ：ステアリングギア比
Ｖ：車速
θ：ハンドル操舵角
γ：ヨーレート
ｓ：ラプラス演算子
Ａ：スタビリティファクタ
であり、Ａは次式により表される。
【数３】

上記ハンドル角からヨーレートへの伝達関数は、簡易的に、次のような形で表すことができる
【数４】

上記伝達関数よりヨーレートからハンドル角への伝達関数は次のような形で表すことができる。
【数５】

このままでは実現不可能なので、この伝達関数に次のような位相補償のＬＰＦを加える。
【数６】

最終的に、ヨーレートからハンドル角への伝達関数に上記位相補償ＬＰＦを加えて、次のような伝達関数で実現することができる。
【数７】

これをよく知られた手法にて離散化することにより、次のような形にしてマイコンで実現する。
【数８】

【００４６】
横加速度の位相補償の場合：
ハンドル角から横Ｇへの伝達関数は次式により表される。
【数９】

上記伝達関数よりヨーレートからハンドル角への伝達関数は次のような形で表すことができる。
【数１０】

これをよく知られた手法にて離散化することにより、ヨーレートのときと同様の形をとる。
【００４７】
横滑り角の位相補償の場合：
ハンドル角から横滑り角への伝達関数は次式のように表すことができ、伝達関数としては、ヨーレートのときと同様の形をとる。
【数１１】

【００４８】
本実施の形態５の場合には、ヨーレートは、ハンドル角に対して時定数が１Ｈｚ強の位相遅れの特性を有するので、速く操舵した場合には、重畳反力トルクの位相がハンドルの角度に対して若干遅れるため、運転者が違和感を感じる場合がある。これを防止するために、ハンドル角に対するヨーレートの伝達関数の逆関数に相当する位相補償器に通して位相を進めたヨーレートに対してゲインを乗ずるようにしておけば、車両挙動が安定している場合には、ハンドル角にゲインを乗じた場合と同様の操舵フィーリングが得られる。また、例えば低μ路において、図１５に示すようなハンドル操作で、図１６のように車両がスピンした場合には、高μ路等で通常走行した場合よりもヨーレートは大きくでる。その結果、ヨーレートＦ／Ｂした方が、操舵角Ｆ／Ｂした場合よりも、ハンドル戻し電流Ｉｔｉｒｅが大きく、即ち、重畳反力トルクも大きくなるので（図１７参照）、スピンし始めた場合のカウンタステアも容易にできる。
【００４９】
実施の形態６．
図１８は、本発明の実施の形態６の機能構成を示すブロック図である。この図において、一点鎖線で囲まれた部分が、電動機１０５に印加する電流の目標値を演算する部分である。
【００５０】
この実施の形態６は、ステアリング軸反力トルクを操舵トルク検出器１３１の出力と電動機１０５の電流を検出するモータ電流検出器１４７の出力から推定して用いる点以外は、上記実施の形態１と全く同様である。
【００５１】
この実施の形態６の動作を図１９のフローチャートに基づいて説明する。このフローチャートは、上記実施の形態１における図３のステップＳ３の動作「ステアリング軸反力トルク読み込みメモリに記憶」を具体的に表したものである。
【００５２】
先ず、ステップＳ３１において、操舵トルクＴｈｄｌを読み込んでメモリに記憶し、ステップＳ３２で、電動機１０５の電流を検出するモータ電流検出器１４７の出力Ｔａｓｓｉｓｔを読み込んでメモリに記憶し、次にステップＳ３３で、ステアリング軸反力トルクＴｔｒａｎを、操舵トルクＴｈｄｌとモータ電流検出器１４７の出力Ｔａｓｓｉｓｔとから推定し、ステップＳ３４で、このようにして推定したステアリング軸反力トルクＴｔｒａｎをメモリに記憶する。
【００５３】
ステアリング軸反力トルクＴｔｒａｎは、一般的に、特に電動機１０５の慣性モーメントが大きくない場合には、下式の関係で、操舵トルクＴｈｄｌ、電動機１０５によるアシストトルクＴａｓｓｉｓｔと釣り合う。
Ｔｔｒａｎ ＝ Ｔｈｄｌ ＋ Ｔａｓｓｉｓｔ
このうち、操舵トルクＴｈｄｌは、電動パワーステアリングでは、必ず測定するものであり既知である。また、電動機１０５によるアシストトルクＴａｓｓｉｓｔは、次式の関係が成立する。
Ｔａｓｓｉｓｔ ＝ Ｇｇｅａｒ・Ｋｔ・Ｉｍｔｒ
【００５４】
この実施の形態６の場合には、ステアリング軸反力トルクセンサを追加する必要がなくなる。その他の効果については、上記実施の形態１と全く同様である。
【００５５】
実施の形態７．
図２０は、本発明の実施の形態７の機能構成を示すブロック図である。この図において、一点鎖線で囲まれた部分が、電動機１０５に印加する電流の目標値を演算する部分である。
【００５６】
この実施の形態７は、ステアリング軸反力トルクを、操舵トルク検出器１３１の出力と電動機１０５の電流を検出するモータ電流検出器１４７の出力とに加えて、電動機１０５の回転加速度を検出するモータ加速度検出器１３９の出力も用いて推定する点以外は、上記実施の形態６と全く同様である。
【００５７】
この実施の形態７の動作を図２１のフローチャートに基づいて説明する。このフローチャートは、上記実施の形態１における図３のステップＳ３の動作「ステアリング軸反力トルクを読み込みメモリに記憶」について具体的に表したものである。
【００５８】
上記実施の形態６では、ステアリング軸反力トルクＴｔｒａｎを操舵トルクＴｈｄｌとモータ電流検出器１４７の出力Ｔａｓｓｉｓｔから推定したが、本実施の形態７では、電動機１０５の回転加速度も加えて推定する。その他は上記実施の形態６と全く同様である。
【００５９】
すなわち、本実施の形態７では、ステップＳ３２の後に、ステップＳ３５において、モータ加速度検出器１３９よりモータ加速度を読み込んでメモリに記憶し、次いでステップＳ３３Ａで、ステアリング軸反力トルクＴｔｒａｎを、操舵トルクＴｈｄｌと、モータ電流検出器１４７の出力Ｔａｓｓｉｓｔと、モータ加速度検出器１３９の出力とから推定し、ステップＳ３４で、このようにして推定したステアリング軸反力トルクＴｔｒａｎをメモリに記憶する。
【００６０】
ステアリング軸反力トルクＴｔｒａｎは、下式の関係で、操舵トルクＴｈｄｌ、電動機１０５によるアシストトルクＴａｓｓｉｓｔ、電動機１０５の慣性トルクＪ・ｄω／ｄｔと釣り合う。
Ｔｔｒａｎ ＝ Ｔｈｄｌ ＋ Ｔａｓｓｉｓｔ − Ｊ・ｄω／ｄｔ
このうち、操舵トルクＴｈｄｌは、電動パワーステアリングでは、必ず測定するものであり既知である。また、上述したように、電動機１０５によるアシストトルクＴａｓｓｉｓｔは、次式の関係が成立する。
Ｔａｓｓｉｓｔ ＝ Ｇｇｅａｒ・Ｋｔ・Ｉｍｔｒ
【００６１】
この実施の形態７の作用効果は上記実施の形態６と同様である。
【００６２】
実施の形態８．
図２２は、本発明の実施の形態８の機能構成を示すブロック図である。この図において、一点鎖線で囲まれた部分が、電動機１０５に印加する電流の目標値を演算する部分である。
【００６３】
この実施の形態８は、ステアリング軸反力トルクを操舵トルク検出器１３１の出力とモータ電流検出器１４７の出力とに加えて、モータ加速度検出器１３９の出力も用いて推定する点、路面反力トルクをステアリング軸反力トルクから推定し、ゲインをステアリング軸反力トルク検出器１３３の出力に応じて変更すること以外は、実施の形態３と全く同様である。
その原理並びに効果は、請求項６の効果の欄と全く同様である。
【００６４】
この実施の形態８の動作を図２３のフローチャートに基づいて説明する。このフローチャートは、上記実施の形態３における図１０のステップＳ３の動作「ステアリング軸反力トルクを読み込みメモリに記憶」及びステップＳ１２の動作「路面反力トルクを読み込みメモリに記憶」について具体的に表したものである。
【００６５】
すなわち、ステップＳ３１乃至ステップＳ３４までのステアリング軸反力トルクを推定するまでの動作は上記実施の形態７と同様であり、ステップＳ３５において、推定したステアリング軸反力トルクから路面反力を推定しており、これ以外は実施の形態３と全く同様である。
【００６６】
路面反力Ｔａｌｉｇｎは、ステアリング軸反力トルクＴｔｒａｎから摩擦項Ｔｆｒｐ・ｓｇｎ（ω）を減算したものであり、次式により表される。
Ｔａｌｉｇｎ ＝ Ｔｔｒａｎ− Ｔｆｒｐ・ｓｇｎ（ω）
【００６７】
この実施の形態８の場合には、ラック・アンド・ピニオン機構のラックにロードセルを配置するなどした新たなセンサを設ける必要がなくなる。その他の効果については上記実施の形態３と同様である。
【００６８】
【発明の効果】
以上のように、本発明に係る電動式パワーステアリング制御装置は、操舵系の反力トルクを検出するステアリング軸反力トルクセンサと、前記操舵角センサにより検出された操舵角にゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記操舵系の反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記操舵系の反力が小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクを演算するためのゲインを可変とすることにより、ステアリング軸反力トルクが大きい時には、重畳反力トルクを低減させ、ステアリング軸反力が小さい時には重畳反力トルクを増大させることが可能となるため、重畳反力トルクを加えた補償後のステアリング軸反力は、ゲイン一定の場合に比べて、必要以上に補償後のステアリング軸反力を大きくすることなしに、ハンドルの戻り量を向上させることが可能となる。また、滑りやすい路面では、ゲイン一定の場合、ハンドルを切り込んでいった場合の路面反力の低下が判りにくくなるが、ハンドル戻し方向のトルクを演算するゲインを可変とすることにより、滑りやすい感触を運転者が判り易くなるので、滑りやすい路面での運転者のハンドルの切り過ぎを防止できる。
【００６９】
また、本発明に係る電動式パワーステアリング制御装置は、操舵ハンドルの中立位置からの回転角度を表す操舵角を検出する操舵角センサと、車両の走行する路面の反力トルクを求める路面反力トルク決定部と、前記操舵角センサにより検出された操舵角にゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記路面反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記路面反力トルクが小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクを演算するためのゲインを可変とすることにより、ステアリング軸反力トルクが大きい時には、重畳反力トルクを低減させ、ステアリング軸反力が小さい時には重畳反力トルクを増大させることが可能となるため、重畳反力トルクを加えた補償後のステアリング軸反力は、ゲイン一定の場合に比べて、必要以上に補償後のステアリング軸反力を大きくすることなしに、ハンドルの戻り量を向上させることが可能となる。また、滑りやすい路面では、ゲイン一定の場合、ハンドルを切り込んでいった場合の路面反力の低下が判りにくくなるが、ハンドル戻し方向のトルクを演算するゲインを可変とすることにより、滑りやすい感触を運転者が判り易くなるので、滑りやすい路面での運転者のハンドルの切り過ぎを防止できる。さらに、重畳反力トルクを操舵角とゲインとの積とすることにより、ハンドル角を検出することなく、ステアリング軸反力が小さい場合には、ハンドルの切り込み角度にほぼ比例した重畳反力トルクを発生させ、ステアリング軸反力が大きい場合には、重畳反力トルクを小さくすることが実現できる。
【００７０】
さらに、本発明に係る電動式パワーステアリング制御装置は、操舵系の反力トルクを検出するステアリング軸反力トルクセンサと、車両の走行する路面の反力トルクを求める路面反力トルク決定部と、前記路面反力トルク決定部にで求められた路面反力にゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記操舵系の反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記操舵系の反力が小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクを演算するためのゲインを可変とすることにより、ステアリング軸反力トルクが大きい時には、重畳反力トルクを低減させ、ステアリング軸反力が小さい時には重畳反力トルクを増大させることが可能となるため、重畳反力トルクを加えた補償後のステアリング軸反力は、ゲイン一定の場合に比べて、必要以上に補償後のステアリング軸反力を大きくすることなしに、ハンドルの戻り量を向上させることが可能となる。また、滑りやすい路面では、ゲイン一定の場合、ハンドルを切り込んでいった場合の路面反力の低下が判りにくくなるが、ハンドル戻し方向のトルクを演算するゲインを可変とすることにより、滑りやすい感触を運転者が判り易くなるので、滑りやすい路面での運転者のハンドルの切り過ぎを防止できる。さらに、ラック・アンド・ピニオン機構のラックにロードセルを設けること等により、路面反力トルクを直接測定する場合には、ステアリング軸反力トルクでなく、路面反力トルクに基づいてゲインを変更する。
【００７１】
さらにまた、本発明に係る電動式パワーステアリング制御装置は、車両の走行する路面の反力トルクを求める路面反力トルク決定部と、前記路面反力トルク決定部により求められた路面反力トルクにゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記路面反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記路面反力トルクが小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクを演算するためのゲインを可変とすることにより、ステアリング軸反力トルクが大きい時には、重畳反力トルクを低減させ、ステアリング軸反力が小さい時には重畳反力トルクを増大させることが可能となるため、重畳反力トルクを加えた補償後のステアリング軸反力は、ゲイン一定の場合に比べて、必要以上に補償後のステアリング軸反力を大きくすることなしに、ハンドルの戻り量を向上させることが可能となる。また、滑りやすい路面では、ゲイン一定の場合、ハンドルを切り込んでいった場合の路面反力の低下が判りにくくなるが、ハンドル戻し方向のトルクを演算するゲインを可変とすることにより、滑りやすい感触を運転者が判り易くなるので、滑りやすい路面での運転者のハンドルの切り過ぎを防止できる。さらに、ラック・アンド・ピニオン機構のラックにロードセルを設けること等により、路面反力トルクを直接測定する場合には、ステアリング軸反力トルクでなく、路面反力トルクに基づいてゲインを変更することができる。
【００７２】
また、本発明に係る電動式パワーステアリング制御装置は、操舵系の反力トルクを検出するステアリング軸反力トルクセンサと、車両のヨーレート、横加速度、横滑り角のうちの何れかの状態量を検出する状態量センサと、前記状態量センサにより検出された車両のヨーレート、横加速度、横滑り角のうちの何れかの状態量にゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記操舵系の反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記操舵系の反力が小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクをヨーレート、横加速度、横滑り角の内の何れかの状態量とゲインとの積とすることにより、車両挙動に応じた重畳反力トルクを発生させることができるようになり、車両状態が不安定な場合等で、ハンドル角と車両挙動の関係が通常走行時と異なる場合にも、適切な重畳反力トルクを与えることができる。
【００７３】
さらに、本発明に係る電動式パワーステアリング制御装置は、車両のヨーレート、横加速度、横滑り角のうちの何れかの状態量を検出する状態量センサと、車両の走行する路面の反力トルクを決定する路面反力トルク決定部と、前記状態量センサにより検出された車両のヨーレート、横加速度、横滑り角のうちの何れかの状態量にゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記路面反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記路面反力トルクが小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクをヨーレート、横加速度、横滑り角の内の何れかの状態量とゲインとの積とすることにより、車両挙動に応じた重畳反力トルクを発生させることができるようになり、車両状態が不安定な場合等で、ハンドル角と車両挙動の関係が通常走行時と異なる場合にも、適切な重畳反力トルクを与えることができる。
【００７４】
さらにまた、本発明に係る電動式パワーステアリング制御装置は、操舵ハンドルの中立位置からの回転角度を表す操舵角を検出する操舵角センサと、操舵系に接続された動力操舵用の電動機に供給されるモータ電流を検出するモータ電流検出器と、自動車の運転者が操舵する際のトルクを検出する操舵トルクセンサと、前記モータ電流検出器により検出されたモータ電流と前記操舵トルクセンサにより検出された操舵トルクとから操舵系の反力トルクを推定するステアリング軸反力トルク演算部と、前記操舵角センサにより検出された操舵角にゲインを乗じて操舵ハンドルの戻し方向の重畳反力トルクを演算する重畳反力トルク演算部と、前記操舵系の反力トルクが大きい時には、前記重畳反力トルクを低減させ、前記操舵系の反力が小さい時には、前記重畳反力トルクを増大させるように前記ゲインを制御する制御部と、を備えるので、重畳反力トルクを演算するためのゲインを可変とすることにより、ステアリング軸反力トルクが大きい時には、重畳反力トルクを低減させ、ステアリング軸反力が小さい時には重畳反力トルクを増大させることが可能となるため、重畳反力トルクを加えた補償後のステアリング軸反力は、ゲイン一定の場合に比べて、必要以上に補償後のステアリング軸反力を大きくすることなしに、ハンドルの戻り量を向上させることが可能となる。また、滑りやすい路面では、ゲイン一定の場合、ハンドルを切り込んでいった場合の路面反力の低下が判りにくくなるが、ハンドル戻し方向のトルクを演算するゲインを可変とすることにより、滑りやすい感触を運転者が判り易くなるので、滑りやすい路面での運転者のハンドルの切り過ぎを防止できる。さらに、重畳反力トルクを操舵角とゲインとの積とすることにより、ハンドル角を検出することなく、ステアリング軸反力が小さい場合には、ハンドルの切り込み角度にほぼ比例した重畳反力トルクを発生させ、ステアリング軸反力が大きい場合には、重畳反力トルクを小さくすることが実現できる。
【００７５】
また、前記操舵系の反力トルクＴｔｒａｎは、下記の式、
Ｔｔｒａｎ ＝ Ｔｈｄｌ ＋ Ｔａｓｓｉｓｔ − Ｊ・ｄｗ／ｄｔ
ここで、Ｔｈｄｌは操舵トルク、Ｔａｓｓｉｓｔはモータによるアシストトルク、Ｊ・ｄｗ／ｄｔはモータの慣性トルク、
により求めるので、一般的に、特に摩擦の大きさＴｆｒｐは既知であるため、電動機の回転方向さえ判れば補償可能であり、電動機の回転方向は、電動機や、逆起電圧の推定値から判るので補償を行うことができる。また、この場合にも、ラック・アンド・ピニオン機構のラックにロードセルを配置するなどした新たなセンサを設ける必要が無くなる。
【００７６】
さらに、前記路面反力トルクは、前記操舵系の反力トルクから前記操舵系の摩擦トルクを減算して求めるので、路面反力トルクを実測する必要が無く、従って路面反力トルクセンサを設ける必要が無くなる。
【図面の簡単な説明】
【図１】 本発明に係る電動式パワーステアリング制御装置の概略構成を示す図である。
【図２】 本発明の実施の形態１によるＥＣＵの機能構成を示すブロック図である。
【図３】 本発明の実施の形態１による戻しトルク補償部の動作を表すフローチャートである。
【図４】 本発明の実施の形態１におけるステアリング軸反力とゲインとの関係を示すマップ図である。
【図５】 本発明の実施の形態１におけるハンドル角とステアリング軸反力トルクとの関係を示す図で、（ａ）は本発明の場合、（ｂ）は従来例の場合をそれぞれ表している。
【図６】 本発明の実施の形態１における滑りやすい路面でのハンドル角とステアリング軸反力トルクとの関係を示す図で、（ａ）は本発明の場合、（ｂ）は従来例の場合をそれぞれ表している。
【図７】 本発明の実施の形態２によるＥＣＵの機能構成を示すブロック図である。
【図８】 本発明の実施の形態２の戻しトルク補償部の動作を表すフローチャートである。
【図９】 本発明の実施の形態３によるＥＣＵの機能構成を示すブロック図である。
【図１０】 本発明の実施の形態３の戻しトルク補償部の動作を表すフローチャートである。
【図１１】 本発明の実施の形態４によるＥＣＵの機能構成を示すブロック図である。
【図１２】 本発明の実施の形態４の戻しトルク補償部の動作を表すフローチャートである。
【図１３】 本発明の実施の形態５によるＥＣＵの機能構成を示すブロック図である。
【図１４】 本発明の実施の形態５の戻しトルク補償部の動作を表すフローチャートである。
【図１５】 本発明の実施の形態５におけるハンドル角の時間応答を示す図である。
【図１６】 本発明の実施の形態５におけるヨーレートの時間応答を示す図である。
【図１７】 本発明の実施の形態５におけるハンドル戻しトルクの時間応答を示す図である。
【図１８】 本発明の実施の形態６によるＥＣＵの機能構成を示すブロック図である。
【図１９】 本発明の実施の形態６の戻しトルク補償部の動作の一部を表すフローチャートである。
【図２０】 本発明の実施の形態７によるＥＣＵの機能構成を示すブロック図である。
【図２１】 本発明の実施の形態７の戻しトルク補償部の動作の一部を表すフローチャートである。
【図２２】 本発明の実施の形態８によるＥＣＵの機能構成を示すブロック図である。
【図２３】 本発明の実施の形態８の戻しトルク補償部の動作の一部を表すフローチャートである。
【図２４】 従来の電動式パワーステアリング制御装置の概略構成図である。
【図２５】 従来の電動式パワーステアリング制御装置における、電動機を制御する制御手段の機能構成を示す図である。
【符号の説明】
１０１ 操舵ハンドル、１０３ トルクセンサ、１０５ 電動機、１０７ ハンドル角センサ、１１１ ＥＣＵ、１２１ 操舵トルク制御器、１２３ 戻しトルク補償器、１２５ ダンピング補償器、１２７ 慣性補償器、１２９ 車速検出器、１３１ 操舵トルク検出器、１３３ ステアリング軸反力トルク検出器、１３５ ハンドル角検出器、１３７ モータ速度検出器、１３９ モータ加速度検出器、１４１ 加算器、１４３ 減算器、１４５ モータ駆動器、１４７ モータ電流検出器、１４９ 路面反力トルク検出器、１５１ ヨーレート検出器、１５３ ヨーレート位相検出器。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an electric power steering device that assists a steering operation by a driver with an electric motor connected to a steering system, and in particular, an electric power that applies a reaction torque according to a steering angle of the steering system. In the steering device, the reaction force torque is corrected based on the reaction force of the steering system, thereby improving the steering control performance while the vehicle is traveling on a road surface having a low friction coefficient.
[0002]
[Prior art]
Conventionally, an electric motor is connected to a steering system that converts a steering angle given to a steering wheel by a driver into a steering angle of a wheel, and the driving force of the electric motor is added to the steering system to reduce the steering force of the driver. Such an electric power steering device is known. A typical example of such an electric power steering apparatus is shown in FIG.
[0003]
The electric power steering apparatus shown in FIG. 24 is connected to a steering shaft 2 integrally coupled to the steering handle 1 via a coupling shaft 3 having universal joints 3a and 3b, and meshes with the pinion 4 The rack shaft 8 is capable of reciprocating in the vehicle width direction and is connected to the knuckle arms 7 and 7 (only one is shown in FIG. 24) of the left and right front wheels 6 and 6 via the tie rods 5 and 5 at both ends. A manual steering force generating mechanism 9 composed of a configured rack and pinion mechanism and a rack shaft 8 so as to generate an auxiliary steering force for reducing the steering force generated by the manual steering force generating mechanism 9 Coaxially arranged and connected electric motor 10, steering force detection means 11 for detecting the manual steering force of the driver acting on the pinion 4, and the rotation angle of the steering handle 1 are detected. And a control means 13 for controlling the output of the electric motor 10 based on the detection value TP of the steering force detection means 11 and the detection value θ of the steering angle detection means 12. Yes.
[0004]
As shown in FIG. 25, the control means 13 sets a target torque to be generated by the electric motor 10 and outputs an output target value generating means 14 for outputting the target torque value, and the output target value generating means 14 outputs the target torque. Motor driving means 15 for driving and controlling the electric motor 10 based on the target torque value, and the auxiliary steering force generated by the electric motor 10 is controlled based on the output TP of the steering force detecting means 11.
[0005]
[Problems to be solved by the invention]
By the way, in the above-described conventional electric power steering device, when steering on a road surface with a low coefficient of friction such as a snowy road, the auxiliary steering force tends to be excessive because the road surface reaction force is small, and the driver feels uncomfortable. There was a problem of giving.
[0006]
In order to improve such an inconvenience, that is, the tendency to cut the steering wheel 1 too much on a slippery road surface, Japanese Patent Application Laid-Open No. 64-74168 discloses a steering wheel under a predetermined traveling condition. A power steering apparatus configured to be able to impart rotational resistance is disclosed.
[0007]
However, this technique controls the rotational resistance applied to the steering system in accordance with, for example, the road surface friction coefficient, and thus has a disadvantage that resistance is also applied to the steering wheel returning operation.
[0008]
Furthermore, in Japanese Patent Laid-Open No. 9-58506, based on the steering force value applied to the manual steering system by the driver and the maximum allowable steering angle value of the manual steering system set based on the friction coefficient of the road surface, There is disclosed a power regulation control device for a steering device that controls the output of an electric motor that generates power to be applied to a manual steering system.
[0009]
However, this technique controls the output torque of the electric motor so that the steering reaction force increases as the steering angle of the manual steering system approaches the limit steering angle (maximum allowable steering angle value) to reduce the assist by the electric motor. The driver has a problem that it is difficult to obtain a feel of a slippery road surface, and further, the driver tends to cut the steering wheel too much. Furthermore, with this technology, it is necessary to detect the friction coefficient of the road surface, but the friction coefficient of the road surface is often different between the left and right wheels, such as when snow remains only on the road shoulder side. Due to the change, there is a problem that it is difficult to accurately detect the road friction coefficient.
[0010]
Accordingly, the present invention is intended to solve the above-described problems, and an object of the present invention is to provide a motor control device for a steering device that can apply an appropriate steering reaction force to a steering wheel in accordance with traveling conditions. It is what.
[0011]
[Means for Solving the Problems]
In order to achieve this object, an electric power steering control device according to the present invention includes a steering shaft reaction force torque sensor for detecting a reaction torque of a steering system, and a gain obtained by multiplying a steering angle detected by the steering angle sensor. A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the steering wheel return direction, and when the reaction force torque of the steering system is large, the superimposed reaction force torque is reduced and the reaction force of the steering system is reduced. torque And a control unit that controls the gain so as to increase the superimposed reaction force torque.
[0012]
An electric power steering control device according to the present invention includes a steering angle sensor that detects a steering angle that represents a rotation angle from a neutral position of a steering wheel, and a road surface on which the vehicle travels. Road surface A road surface reaction force torque determining unit for obtaining a reaction force torque, a superimposed reaction force torque calculating unit for calculating a superimposed reaction force torque in a steering wheel return direction by multiplying a steering angle detected by the steering angle sensor by a gain, and A controller that controls the gain to reduce the superimposed reaction force torque when the road surface reaction torque is large and to increase the superimposed reaction force torque when the road surface reaction torque is small. It is what.
[0013]
The electric power steering control device according to the present invention further includes a steering shaft reaction force torque sensor that detects a reaction force torque of the steering system, and a vehicle that is in a state quantity obtained by subtracting a friction term from the steering shaft reaction force torque. Road surface Road surface The road surface reaction force torque determination unit for obtaining the reaction force torque and the road surface reaction force obtained by the road surface reaction force torque determination unit. torque A superimposed reaction force torque calculator for calculating a superimposed reaction force torque in the steering wheel return direction by multiplying by a gain, and when the reaction torque of the steering system is large, the superimposed reaction force torque is reduced, And a control unit that controls the gain so as to increase the superimposed reaction torque when the reaction torque is small.
[0014]
Furthermore, the electric power steering control device according to the present invention provides a road surface on which the vehicle travels. Road surface A road surface reaction torque determining unit for obtaining a reaction torque, and a superimposed reaction force torque for calculating a superimposed reaction force torque in the steering wheel return direction by multiplying the road surface reaction torque obtained by the road surface reaction torque determining unit by a gain. When the road surface reaction torque, which is a state quantity obtained by subtracting the friction term from the steering shaft reaction torque, is large, that is, when the steering shaft reaction torque is large, the superimposed reaction torque is reduced and the road reaction torque is reduced. And a control unit that controls the gain so as to increase the superimposed reaction force torque when the force torque is small, that is, when the steering shaft reaction force torque is small.
[0015]
The electric power steering control device according to the present invention also detects a steering shaft reaction force torque sensor that detects a reaction torque of a steering system, and a state quantity of any of a yaw rate, a lateral acceleration, and a skid angle of a vehicle. A state quantity sensor that performs a superimposition reaction force torque in the steering wheel return direction by multiplying a state quantity of the vehicle yaw rate, lateral acceleration, or skid angle detected by the state quantity sensor by a gain. When the reaction torque of the reaction force torque calculation unit and the steering system is large, the superimposed reaction force torque is reduced and the reaction force of the steering system is reduced. torque And a control unit that controls the gain so as to increase the superimposed reaction force torque.
[0016]
Furthermore, an electric power steering control device according to the present invention includes a state quantity sensor that detects any state quantity among a yaw rate, a lateral acceleration, and a skid angle of a vehicle, and a road surface on which the vehicle travels. Road surface A road surface reaction force torque determination unit for determining reaction force torque, and a state amount detected by the state quantity sensor by multiplying any one of the vehicle yaw rate, lateral acceleration, and sideslip angle by a gain in the return direction of the steering wheel. A superimposed reaction force torque calculation unit that calculates a superimposed reaction force torque; and when the road surface reaction force torque is large, the superimposed reaction force torque is reduced, and when the road surface reaction torque is small, the superimposed reaction force torque is increased. A control unit for controlling the gain as described above.
[0017]
Furthermore, an electric power steering control device according to the present invention is supplied to a steering angle sensor that detects a steering angle that represents a rotation angle from a neutral position of a steering wheel, and a power steering electric motor that is connected to a steering system. A motor current detector for detecting a motor current, a steering torque sensor for detecting a torque when the driver of the automobile steers, a motor current detected by the motor current detector and a steering torque sensor Steering shaft reaction force torque calculation unit for estimating reaction torque of the steering system from the steering torque, and multiplying the steering angle detected by the steering angle sensor by a gain to calculate a superimposed reaction force torque in the return direction of the steering wheel When the reaction force torque of the superposed reaction force torque calculation unit and the steering system is large, the superposition reaction force torque is reduced and the reaction force of the steering system is reduced. torque And a control unit that controls the gain so as to increase the superimposed reaction force torque.
[0018]
The reaction torque Ttran of the steering system is expressed by the following equation:
Ttran = Thdl + Tassist−J · dw / dt
Here, Thdl is the steering torque, Tassist is the assist torque by the motor, J · dw / dt is the inertia torque of the motor,
It is characterized by calculating | requiring by.
[0019]
Further, the road surface reaction torque is obtained by subtracting the steering system friction torque from the steering system reaction torque.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0021]
Embodiment 1 FIG.
FIG. 1 is a diagram showing a schematic configuration of an electric power steering control device according to the present invention. The electric power steering control device of FIG. 1 measures the steering torque Thdl applied to the steering system when the driver turns the steering wheel 101 with the torque sensor 103, and uses the electric motor 105 to determine the assist torque Tassist according to the steering torque. It is the main function to generate. Further, in order to realize better steering feeling and steering stability, a handle angle sensor 107 that detects a rotation angle (handle angle) of the steering handle 101, a rotation angle (motor angle) or a rotation speed (motor angular speed) of the electric motor 105. A rotation sensor (not shown) that detects (which may be differentiated to obtain motor angular acceleration) may be provided, and these outputs may be input to the electronic control unit (ECU) 111. Further, the current (current detection signal) flowing through the electric motor 105 and the voltage (voltage detection signal) applied between the motor terminals are also taken into the ECU 111.
[0022]
Dynamically, the sum of the steering torque Thdl and the assist torque Tassist rotates the steering system against the steering system reaction force (hereinafter referred to as steering shaft reaction torque) Ttran. In addition, when the steering handle 101 is rotated, the inertial force J · dw / dt of the electric motor 105 also acts, and eventually the relationship of the following equation is established.
Ttran = Thdl + Tassist−J · dw / dt
[0023]
The assist torque Tassist by the electric motor 105 has the following relationship.
Tassist = Ggear · Kt · Imtr
Here, Ggear is a gear ratio of a reduction gear that transmits assist torque from the electric motor 105 to the steering shaft 101, Kt is a torque constant, and Imtr is a current (motor current) flowing through the electric motor 105.
[0024]
Further, the steering shaft reaction force torque Ttran is the sum of the road surface reaction torque Talign representing the reaction force from the road surface on which the vehicle travels and the friction torque Tfric in the steering mechanism.
[0025]
The ECU 111 calculates a target value (motor current target value) of current supplied to the electric motor 105 from the various sensor signals described above, and the current so that the actual current flowing through the electric motor 105 matches the motor current target value. Take control. Accordingly, the electric motor 105 generates a predetermined torque obtained by multiplying the current value Imtr by the torque constant Kt and the gear ratio Ggear, and assists the torque generated by the driver's steering.
[0026]
FIG. 2 is a block diagram showing a functional configuration of ECU 111 according to Embodiment 1 of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0027]
As shown in FIG. 2, the ECU 111 detects a vehicle speed by inputting a vehicle speed signal from a steering torque controller 121, a return torque compensator 123, a damping compensator 125, an inertia compensator 127, a vehicle speed sensor (not shown), and the like. 129, steering torque detector 131 for inputting a steering torque signal from the torque sensor 103, steering shaft reaction force torque detector 133 for inputting a steering shaft reaction force torque signal, and a steering wheel angle (from a steering wheel neutral position). The rotation angle of the motor 105, the motor speed detector 137 for detecting the rotation speed of the motor 105 by inputting the voltage detection signal and the current detection signal from the motor 105, and the motor from the output of the motor speed detector 137. A motor acceleration detector 139 for obtaining 105 rotational acceleration is provided. A vehicle speed detection signal is input to these controllers and compensators, and control parameters are changed based on the input vehicle speed detection signal. The output of the steering torque controller 121 is input to the adder 141. Here, the output of the steering torque controller 121 includes the output of the return torque compensator 121, the output of the damping compensator 125, and the output of the inertia compensator 127. Are added to calculate the current target value. This target current value is input to the subtractor 143, where the output (motor current value) of the motor current detector 147 that detects the current flowing through the motor 105 is subtracted from the target current value and input to the motor driver 145. Is done. The motor driver 145 controls the supply current to the electric motor 105 based on the output signal from the subtracter 143. Here, since the novel element in the present invention is the return torque compensator 123, the return torque compensator 123 will be described in detail below.
[0028]
Hereinafter, the operation of the return torque compensator 123 will be described based on the flowchart of FIG. First, the detected steering torque Thdl is read and stored in the memory (Step S1), the motor speed signal is read and stored in the memory (Step S2), and the steering shaft reaction force torque is further read and stored in the memory (Step S1). S3), the steering angle θhdl is read and stored in the memory (step S4). Next, the motor speed signal is differentiated to calculate the motor acceleration signal (step S5), the basic target current Ibase is calculated based on the steering torque Thdl (step S6), the damping current Idamp is calculated (step S7), and the inertia Compensation current Iiner is calculated (step S8). Next, the steering angle F / B gain is determined from the steering shaft reaction torque according to a map diagram (relationship diagram between the steering shaft reaction force and gain) as shown in FIG. 4 (step S9). When the steering wheel is turned, the steering angle F / B gain is small, and when the steering wheel is returned, the steering angle F / B gain is large. The steering wheel return current Itire is obtained by multiplying the steering angle θhdl by the steering angle F / B gain by the steering shaft reaction torque (step S10). The target return current Iref is calculated by adding the handle return current Itire to the basic target current Ibase (step S11). The steering wheel return current Itire acts as a superimposed reaction force torque.
[0029]
According to the first embodiment, by making the gain for calculating the superimposed reaction force torque variable, the superimposed reaction force torque is reduced when the steering shaft reaction force torque is large, and when the steering shaft reaction force is small, the superimposed reaction force torque is reduced. Since it is possible to increase the force torque, as shown in FIG. 5 (a), the compensated steering shaft reaction force to which the superimposed reaction force torque is applied is compared with the case where the gain is constant (FIG. 5 (b)). Therefore, the return amount of the steering wheel can be improved without increasing the compensated steering shaft reaction force more than necessary. On a slippery road surface, when the gain is constant, the decrease in the road surface reaction force when the handle is cut is difficult to understand (FIG. 6B), but the gain for calculating the torque in the handle return direction can be made variable. This makes it easier for the driver to understand the slippery feel (FIG. 6 (a)), so that it is possible to prevent the driver from turning too much on the slippery road surface.
[0030]
Embodiment 2. FIG.
FIG. 7 is a block diagram showing a functional configuration of the second embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0031]
The return torque compensator 123 calculates a superimposed reaction force torque by multiplying the handle angle detected by the handle angle detector 135 by a gain, and outputs it to the adder 141 that calculates the sum of the outputs of the controllers / compensators. The The gain at this time is changed according to the output of the steering shaft reaction force torque detector 133 in the first embodiment, but is changed based on the output of the road surface reaction force torque detector 149 in the second embodiment. . Except this, it is exactly the same as the first embodiment.
[0032]
The operation of the second embodiment will be described based on the flowchart of FIG. In the first embodiment, the steering shaft reaction force torque is read and stored in the memory in step S3 of the flowchart of FIG. 3, and the steering angle F / B gain is output from the steering shaft reaction force torque detector 133 in step S9. In the second embodiment, as shown in FIG. 8, after the motor speed signal is read and stored in the memory in step S2, the road surface reaction force torque is read and stored in the memory in step S12. In step S9A after step S8, the steering angle F / B gain is changed based on the output of the road surface reaction force torque detector 149. In step S10, the steering angle by the road surface reaction force torque is changed to the steering angle θhdl. The handle return current Itire is obtained by multiplying the F / B gain. The other steps of the second embodiment are exactly the same as those of the first embodiment.
[0033]
In the second embodiment, the same effect as described in the first embodiment can be expected, and when the road surface reaction force torque is directly measured by providing a load cell in the rack of the rack and pinion mechanism, etc. As in the second embodiment, the gain may be changed based on the road surface reaction torque instead of the steering shaft reaction torque.
[0034]
Embodiment 3 FIG.
FIG. 9 is a block diagram showing a functional configuration of the third embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105. In the third embodiment, a road surface reaction torque detector 149 that detects road surface reaction torque is provided in place of the handle angle detector 135 of the first embodiment.
[0035]
In the first embodiment, the superimposed reaction force torque is calculated by multiplying the steering wheel angle by the gain. However, in the third embodiment, the superimposed reaction force torque is calculated by multiplying the road surface reaction force torque by the gain. That is, after step S2, in step S12, the road surface reaction torque is read and stored in the memory, and in step S13, the steering shaft reaction torque is read and stored in the memory. 4, after determining the steering angle F / B gain according to the map diagram as shown in FIG. 4, in step S <b> 10 </ b> B, the road reaction force torque from the road surface reaction torque detector 149 is multiplied by the gain to calculate the superimposed reaction force torque. The superimposed reaction force torque is output to the adder 141 that calculates the sum of the outputs of the controllers / compensators. The third embodiment is exactly the same as the first embodiment except for this, and the gain is changed according to the output of the steering shaft reaction force torque detector 133. When the handle is cut, the road surface reaction torque F / B gain is small, and when the handle is returned, the road surface reaction torque F / B gain is large.
[0036]
According to the third embodiment, even if the steering wheel angle is not detected, if the steering shaft reaction force is small, a superimposed reaction force torque that is substantially proportional to the steering angle of the steering wheel is generated, and the steering shaft reaction force is large. In this case, the superimposed reaction force torque can be reduced.
[0037]
Embodiment 4 FIG.
FIG. 11 is a block diagram showing a functional configuration of the fourth embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0038]
In the first embodiment, the superimposed reaction force torque is calculated by multiplying the handle angle by the gain. In the fourth embodiment, the superimposed reaction force torque is calculated by multiplying the yaw rate by the gain, and each controller / compensator is calculated. Is output to an adder 141 that calculates the sum of the outputs of the two outputs. Except this, it is exactly the same as in the first embodiment, and the gain is changed according to the output of the steering shaft reaction force torque detector 133.
[0039]
The operation of the fourth embodiment will be described based on the flowchart of FIG. In the first embodiment, the superimposed reaction force torque is calculated by multiplying the handle angle by the gain. However, in the fourth embodiment, after step S2, the yaw rate γ is read and stored in the memory in step S14, and step S10C. Then, the superimposed reaction force torque is calculated by multiplying the yaw rate γ by the gain. Except this, it is exactly the same as in the first embodiment, and the gain is changed according to the output of the steering shaft reaction force torque detector 133. The yaw rate F / B gain is small when the handle is cut, and the yaw rate F / B gain is large when the handle is returned. Further, instead of the yaw rate γ, a configuration may be employed in which a gain is multiplied by a lateral acceleration or a side slip angle which is a vehicle state quantity other than this.
[0040]
In the case of the fourth embodiment, by setting the superimposed reaction force torque to the product of the yaw rate and the gain, it becomes possible to generate the superimposed reaction force torque according to the vehicle behavior, and the vehicle spins. When the yaw rate is large even though the steering wheel angle is small, a large superimposed reaction torque can be applied, so the driver performs counter-steer operation to prevent spin. It becomes easy.
[0041]
Embodiment 5 FIG.
FIG. 13 is a block diagram showing a functional configuration of the fifth embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0042]
In the fifth embodiment, an adder that calculates the superimposed reaction force torque by multiplying the gain of the yaw rate detected in the fourth embodiment above by phase compensation and calculates the sum of the outputs of the controllers / compensators. 141 is output. Except this, it is exactly the same as in the fourth embodiment, and the gain is changed according to the output of the steering shaft reaction force torque detector 133.
[0043]
The operation of the fifth embodiment will be described based on the flowchart of FIG. In the fifth embodiment, in step S15 after step S8, phase compensation is performed on the yaw rate γ detected in the fourth embodiment as described later, and in step S10D after step S9, the above-described embodiment is performed. 4 is obtained by multiplying the gain γp obtained by phase compensation of the yaw rate γ detected in step 4 by a gain and obtaining the superimposed reaction force torque. Except this, it is exactly the same as in the fourth embodiment, and the gain is changed according to the output of the steering shaft reaction force torque detector 133. When turning the steering wheel, the yaw rate F / B gain is small, and when returning, the yaw rate F / B gain is large. Moreover, it is good also as a structure which multiplies a gain to the lateral acceleration which is a vehicle state quantity other than this, or the skid angle (beta) instead of this.
[0044]
Phase compensation is performed by the following calculation. (Reference: Kabaya Kogyo Co., Ltd .: Control and safety of automobiles, Sankaido, p175 (1996))
[0045]
For yaw rate phase compensation:
The transfer function from the handle angle to the yaw rate is expressed by the following equation.
[Expression 1]

However, D (s) is represented by the following equation.
[Expression 2]

here,
m: Vehicle weight
I: Moment of inertia around the z-axis passing through the center of gravity of the vehicle
L: Wheel base (l = lf + lr)
lf, lr: Horizontal distance from the front and rear axles to the center of gravity
Ff, Fr: front and rear tire cornering force
Kf, Kr: Cornering power of front and rear tires
n: Steering gear ratio
V: Vehicle speed
θ: Steering wheel steering angle
γ: Yaw rate
s: Laplace operator
A: Stability factor
And A is represented by the following equation.
[Equation 3]

The transfer function from the steering wheel angle to the yaw rate can be simply expressed in the following form.
[Expression 4]

From the above transfer function, the transfer function from the yaw rate to the steering wheel angle can be expressed in the following form.
[Equation 5]

Since this cannot be realized as it is, the following phase compensation LPF is added to this transfer function.
[Formula 6]

Finally, the phase compensation LPF is added to the transfer function from the yaw rate to the steering wheel angle, and can be realized by the following transfer function.
[Expression 7]

By discretizing this using a well-known method, it is realized by a microcomputer in the following form.
[Equation 8]

[0046]
For lateral acceleration phase compensation:
The transfer function from the steering wheel angle to the lateral G is expressed by the following equation.
[Equation 9]

From the above transfer function, the transfer function from the yaw rate to the steering wheel angle can be expressed in the following form.
[Expression 10]

By discretizing this by a well-known method, it takes the same form as the yaw rate.
[0047]
For phase compensation of skid angle:
The transfer function from the steering wheel angle to the skid angle can be expressed as the following equation, and the transfer function takes the same form as the yaw rate.
[Expression 11]

[0048]
In the case of the fifth embodiment, the yaw rate has a phase lag characteristic with a time constant of more than 1 Hz with respect to the steering wheel angle. Therefore, when steering is performed quickly, the phase of the superimposed reaction force torque becomes the steering wheel angle. However, the driver may feel uncomfortable because it is slightly delayed. In order to prevent this, if the gain is multiplied by the yaw rate whose phase has been advanced through a phase compensator corresponding to the inverse function of the transfer function of the yaw rate with respect to the steering wheel angle, the vehicle behavior is stable. In this case, the same steering feeling as when the steering wheel angle is multiplied by the gain is obtained. Further, for example, when the vehicle spins as shown in FIG. 16 by a steering operation as shown in FIG. 15 on a low μ road, the yaw rate is larger than when the vehicle travels normally on a high μ road or the like. As a result, since the steering wheel return current Itire is larger when the yaw rate F / B is performed than when the steering angle F / B is performed, that is, the superimposed reaction force torque is also larger (see FIG. 17), Counter steering can be done easily.
[0049]
Embodiment 6 FIG.
FIG. 18 is a block diagram showing a functional configuration of the sixth embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0050]
The sixth embodiment is different from the first embodiment except that the steering shaft reaction force torque is estimated and used from the output of the steering torque detector 131 and the output of the motor current detector 147 for detecting the current of the electric motor 105. It is exactly the same.
[0051]
The operation of the sixth embodiment will be described based on the flowchart of FIG. This flowchart specifically shows the operation “store in the steering shaft reaction force torque reading memory” in step S3 of FIG. 3 in the first embodiment.
[0052]
First, in step S31, the steering torque Thdl is read and stored in the memory, and in step S32, the output Tassist of the motor current detector 147 that detects the current of the electric motor 105 is read and stored in the memory, and then in step S33. The steering shaft reaction force torque Ttran is estimated from the steering torque Thdl and the output Tassist of the motor current detector 147. In step S34, the steering shaft reaction force torque Ttran thus estimated is stored in the memory.
[0053]
In general, the steering shaft reaction force torque Ttran is balanced with the steering torque Thdl and the assist torque Tassist by the electric motor 105 in the following relationship, particularly when the moment of inertia of the electric motor 105 is not large.
Ttran = Thdl + Tassist
Among these, the steering torque Thdl is always measured in the electric power steering and is known. Further, the assist torque Tassist by the electric motor 105 has the following relationship.
Tassist = Ggear · Kt · Imtr
[0054]
In the case of the sixth embodiment, it is not necessary to add a steering shaft reaction force torque sensor. Other effects are the same as those in the first embodiment.
[0055]
Embodiment 7 FIG.
FIG. 20 is a block diagram showing a functional configuration of the seventh embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0056]
In the seventh embodiment, the steering shaft reaction force torque is added to the output of the steering torque detector 131 and the output of the motor current detector 147 that detects the current of the electric motor 105, and the motor that detects the rotational acceleration of the electric motor 105. Except for the point of estimation using also the output of the acceleration detector 139, it is exactly the same as in the sixth embodiment.
[0057]
The operation of the seventh embodiment will be described based on the flowchart of FIG. This flowchart specifically shows the operation “read steering shaft reaction force torque and store it in memory” in step S3 of FIG. 3 in the first embodiment.
[0058]
In the sixth embodiment, the steering shaft reaction torque Ttran is estimated from the steering torque Thdl and the output Tassist of the motor current detector 147. However, in the seventh embodiment, the rotational acceleration of the electric motor 105 is also estimated. Others are exactly the same as in the sixth embodiment.
[0059]
That is, in the seventh embodiment, after step S32, in step S35, the motor acceleration is read from the motor acceleration detector 139 and stored in the memory, and in step S33A, the steering shaft reaction force torque Ttran is changed to the steering torque Thdl. And the output Tassist of the motor current detector 147 and the output of the motor acceleration detector 139. In step S34, the steering shaft reaction force torque Ttran thus estimated is stored in the memory.
[0060]
The steering shaft reaction force torque Ttran balances the steering torque Thdl, the assist torque Tassist by the electric motor 105, and the inertia torque J · dω / dt of the electric motor 105 in the relationship of the following equation.
Ttran = Thdl + Tassist−J · dω / dt
Among these, the steering torque Thdl is always measured in the electric power steering and is known. Further, as described above, the assist torque Tassist by the electric motor 105 has the following relationship.
Tassist = Ggear · Kt · Imtr
[0061]
The operational effects of the seventh embodiment are the same as those of the sixth embodiment.
[0062]
Embodiment 8 FIG.
FIG. 22 is a block diagram showing a functional configuration according to the eighth embodiment of the present invention. In this figure, the part surrounded by the alternate long and short dash line is the part for calculating the target value of the current applied to the electric motor 105.
[0063]
In the eighth embodiment, the steering reaction force torque is estimated using the output of the motor acceleration detector 139 in addition to the output of the steering torque detector 131 and the output of the motor current detector 147. Except that the torque is estimated from the steering shaft reaction force torque and the gain is changed according to the output of the steering shaft reaction force torque detector 133, it is exactly the same as in the third embodiment.
The principle and effect are exactly the same as in the effect column of claim 6.
[0064]
The operation of the eighth embodiment will be described based on the flowchart of FIG. This flowchart specifically shows the operation “step S3 of the steering shaft reaction force torque is read and stored in the memory” and the operation of step S12 “reads the road reaction force torque and stores it in the memory” in the third embodiment. It is a thing.
[0065]
That is, the operation from step S31 to step S34 until the estimation of the steering shaft reaction force torque is the same as that of the seventh embodiment. In step S35, the road surface reaction force is estimated from the estimated steering shaft reaction force torque. Other than this, the configuration is exactly the same as in the third embodiment.
[0066]
The road surface reaction force Talign is a value obtained by subtracting the friction term Tfrp · sgn (ω) from the steering shaft reaction force torque Ttran, and is represented by the following equation.
Talign = Ttran− Tfrp · sgn (ω)
[0067]
In the case of the eighth embodiment, there is no need to provide a new sensor such as placing a load cell in the rack of the rack and pinion mechanism. Other effects are the same as those of the third embodiment.
[0068]
【The invention's effect】
As described above, the electric power steering control device according to the present invention is a steering shaft reaction force torque sensor that detects a reaction force torque of a steering system, and a steering angle detected by the steering angle sensor is multiplied by a gain. When the reaction force torque of the steering system is large, and when the reaction torque of the steering system is large, the superimposed reaction force torque is reduced, and when the reaction force of the steering system is small, And a control unit that controls the gain so as to increase the superimposed reaction force torque, so that when the steering shaft reaction force torque is large by making the gain for calculating the superimposed reaction force torque variable, Since the reaction torque is reduced and the superimposed reaction force torque can be increased when the steering shaft reaction force is small, Tearing shaft reaction force, as compared with the case of the gain constant, without increasing the steering shaft reaction force after compensation than necessary, it is possible to improve the return of the handle. On slippery roads, if the gain is constant, it will be difficult to understand the decrease in the road surface reaction force when the handle is cut, but by making the gain for calculating the torque in the handle return direction variable, the slippery feel Therefore, it is possible to prevent the driver's steering wheel from being overcut on a slippery road surface.
[0069]
The electric power steering control device according to the present invention includes a steering angle sensor that detects a steering angle that represents a rotation angle from a neutral position of a steering handle, and a road surface reaction force torque that calculates a reaction force torque of a road surface on which the vehicle travels. A determining unit, a superimposed reaction force torque calculating unit that calculates a superimposed reaction force torque in a steering wheel return direction by multiplying a steering angle detected by the steering angle sensor, and when the road surface reaction force torque is large, And a control unit that controls the gain so as to increase the superimposed reaction force torque when the road reaction force torque is small when the road surface reaction torque is small. By making the variable, the superimposed reaction force torque is reduced when the steering shaft reaction force torque is large, and the superimposed reaction force torque when the steering shaft reaction force is small. Since it is possible to increase the steering shaft reaction force after compensation with the addition of the superimposed reaction force torque, without increasing the compensated steering shaft reaction force more than necessary compared to the case where the gain is constant, It is possible to improve the return amount of the handle. On slippery roads, if the gain is constant, it will be difficult to understand the decrease in the road surface reaction force when the handle is cut, but by making the gain for calculating the torque in the handle return direction variable, the slippery feel Therefore, it is possible to prevent the driver's steering wheel from being overcut on a slippery road surface. Further, by calculating the superimposed reaction force torque as the product of the steering angle and the gain, when the steering shaft reaction force is small without detecting the steering wheel angle, the superimposed reaction force torque is approximately proportional to the steering angle of the steering wheel. When the steering shaft reaction force is generated, the superimposed reaction force torque can be reduced.
[0070]
Furthermore, an electric power steering control device according to the present invention includes a steering shaft reaction force torque sensor that detects a reaction force torque of a steering system, a road surface reaction force torque determination unit that obtains a reaction force torque of a road surface on which the vehicle travels, A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the steering wheel return direction by multiplying the road surface reaction force obtained by the road surface reaction force torque determination unit by a gain, and a large reaction force torque of the steering system A control unit that controls the gain so as to reduce the superimposed reaction force torque and to increase the superimposed reaction force torque when the reaction force of the steering system is small. By making the gain to be variable, the superimposed reaction force torque is reduced when the steering shaft reaction force torque is large, and the superimposed reaction force torque when the steering shaft reaction force is small. Since it is possible to increase the steering shaft reaction force after compensation with the addition of the superimposed reaction force torque, without increasing the compensated steering shaft reaction force more than necessary compared to the case where the gain is constant, It is possible to improve the return amount of the handle. On slippery roads, if the gain is constant, it will be difficult to understand the decrease in the road surface reaction force when the handle is cut, but by making the gain for calculating the torque in the handle return direction variable, the slippery feel Therefore, it is possible to prevent the driver's steering wheel from being overcut on a slippery road surface. Furthermore, when the road surface reaction torque is directly measured by providing a load cell in the rack of the rack and pinion mechanism, the gain is changed based on the road surface reaction torque instead of the steering shaft reaction torque.
[0071]
Furthermore, the electric power steering control device according to the present invention includes a road surface reaction force torque determining unit that calculates a reaction force torque of a road surface on which the vehicle travels, and a road surface reaction force torque determined by the road surface reaction force torque determining unit. A superimposed reaction force torque calculator that calculates a superimposed reaction force torque in the steering wheel return direction by multiplying the gain, and when the road surface reaction force torque is large, the superimposed reaction force torque is reduced and the road surface reaction torque is small. In some cases, the control unit is configured to control the gain so as to increase the superimposed reaction force torque. Therefore, when the steering shaft reaction force torque is large by making the gain for calculating the superimposed reaction torque variable, Therefore, it is possible to reduce the superimposed reaction force torque and increase the superimposed reaction force torque when the steering shaft reaction force is small. Steering shaft reaction force after compensation were larger than those of a gain constant, without increasing the steering shaft reaction force after compensation than necessary, it is possible to improve the return of the handle. On slippery roads, if the gain is constant, it will be difficult to understand the decrease in the road surface reaction force when the handle is cut, but by making the gain for calculating the torque in the handle return direction variable, the slippery feel Therefore, it is possible to prevent the driver's steering wheel from being overcut on a slippery road surface. Furthermore, when directly measuring road reaction torque by providing a load cell in the rack of the rack and pinion mechanism, the gain should be changed based on the road reaction torque instead of the steering shaft reaction torque. Can do.
[0072]
The electric power steering control device according to the present invention also detects a steering shaft reaction force torque sensor that detects a reaction torque of a steering system, and a state quantity of any of a yaw rate, a lateral acceleration, and a skid angle of a vehicle. A state quantity sensor that performs a superimposition reaction force torque in the steering wheel return direction by multiplying a state quantity of the vehicle yaw rate, lateral acceleration, or skid angle detected by the state quantity sensor by a gain. When the reaction torque of the reaction force torque calculation unit and the steering system is large, the superimposed reaction force torque is reduced, and when the reaction force of the steering system is small, the gain is increased. A control unit for controlling the vehicle behavior by making the superimposed reaction force torque the product of any of the state quantity and gain of yaw rate, lateral acceleration, and skid angle. If the relationship between the steering wheel angle and the vehicle behavior is different from that during normal driving, such as when the vehicle condition is unstable, an appropriate superimposed reaction force torque can be generated. Can be given.
[0073]
Furthermore, the electric power steering control device according to the present invention determines a state quantity sensor that detects any one of a vehicle yaw rate, lateral acceleration, and side slip angle, and a reaction force torque of a road surface on which the vehicle travels. And multiplying the state quantity of the vehicle yaw rate, lateral acceleration, and sideslip angle detected by the state quantity sensor by a gain to obtain the superposed reaction force torque in the return direction of the steering wheel. When the road reaction force torque is large, the superimposed reaction force torque calculating unit is configured to reduce the superimposed reaction force torque, and when the road surface reaction torque is small, the gain is set to increase the superimposed reaction force torque. A control unit for controlling the vehicle behavior by setting the superimposed reaction torque as a product of a state quantity and a gain in any one of yaw rate, lateral acceleration, and sideslip angle. Appropriate superimposed reaction force torque can be generated and the appropriate superimposed reaction force torque can be generated even when the relationship between the steering wheel angle and the vehicle behavior is different from that during normal driving, such as when the vehicle condition is unstable. Can be given.
[0074]
Furthermore, an electric power steering control device according to the present invention is supplied to a steering angle sensor that detects a steering angle that represents a rotation angle from a neutral position of a steering wheel, and a power steering electric motor that is connected to a steering system. A motor current detector for detecting a motor current, a steering torque sensor for detecting a torque when the driver of the automobile steers, a motor current detected by the motor current detector and a steering torque sensor Steering shaft reaction force torque calculation unit for estimating reaction torque of the steering system from the steering torque, and multiplying the steering angle detected by the steering angle sensor by a gain to calculate a superimposed reaction force torque in the return direction of the steering wheel When the reaction torque of the superimposed reaction torque calculation unit and the steering system is large, the superimposed reaction torque is reduced and the reaction force of the steering system is small. Includes a control unit that controls the gain so as to increase the superimposed reaction force torque, so that the steering shaft reaction force torque is increased by making the gain for calculating the superimposed reaction force torque variable. Sometimes, the superimposed reaction force torque can be reduced, and the superimposed reaction force torque can be increased when the steering shaft reaction force is small. Therefore, the compensated steering shaft reaction force with the superimposed reaction force torque has a constant gain. Compared to the case, the return amount of the steering wheel can be improved without increasing the compensated steering shaft reaction force more than necessary. On slippery roads, if the gain is constant, it will be difficult to understand the decrease in the road surface reaction force when the handle is cut, but by making the gain for calculating the torque in the handle return direction variable, the slippery feel Therefore, it is possible to prevent the driver's steering wheel from being overcut on a slippery road surface. Further, by calculating the superimposed reaction force torque as the product of the steering angle and the gain, when the steering shaft reaction force is small without detecting the steering wheel angle, the superimposed reaction force torque is approximately proportional to the steering angle of the steering wheel. When the steering shaft reaction force is generated, the superimposed reaction force torque can be reduced.
[0075]
The reaction torque Ttran of the steering system is expressed by the following equation:
Ttran = Thdl + Tassist−J · dw / dt
Here, Thdl is the steering torque, Tassist is the assist torque by the motor, J · dw / dt is the inertia torque of the motor,
In general, since the friction magnitude Tfrp is already known, it can be compensated only by knowing the rotation direction of the motor, and the rotation direction of the motor can be determined from the estimated value of the motor and the counter electromotive voltage. Compensation can be performed. Also in this case, there is no need to provide a new sensor such as placing a load cell in the rack of the rack and pinion mechanism.
[0076]
Furthermore, since the road surface reaction torque is obtained by subtracting the steering system friction torque from the steering system reaction torque, there is no need to actually measure the road surface reaction torque, and therefore it is necessary to provide a road surface reaction torque sensor. Disappears.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an electric power steering control device according to the present invention.
FIG. 2 is a block diagram showing a functional configuration of the ECU according to the first embodiment of the present invention.
FIG. 3 is a flowchart showing the operation of a return torque compensator according to the first embodiment of the present invention.
FIG. 4 is a map diagram showing a relationship between a steering shaft reaction force and a gain in the first embodiment of the present invention.
5A and 5B are diagrams showing the relationship between the steering wheel angle and the steering shaft reaction torque in the first embodiment of the present invention, where FIG. 5A shows the case of the present invention and FIG. 5B shows the case of the conventional example. .
FIGS. 6A and 6B are diagrams showing a relationship between a steering wheel angle and a steering shaft reaction torque on a slippery road surface according to the first embodiment of the present invention, in which FIG. 6A shows the case of the present invention and FIG. Respectively.
FIG. 7 is a block diagram showing a functional configuration of an ECU according to a second embodiment of the present invention.
FIG. 8 is a flowchart showing the operation of a return torque compensator according to the second embodiment of the present invention.
FIG. 9 is a block diagram showing a functional configuration of an ECU according to a third embodiment of the present invention.
FIG. 10 is a flowchart showing the operation of a return torque compensation unit according to the third embodiment of the present invention.
FIG. 11 is a block diagram showing a functional configuration of an ECU according to a fourth embodiment of the present invention.
FIG. 12 is a flowchart showing the operation of the return torque compensator according to the fourth embodiment of the present invention.
FIG. 13 is a block diagram showing a functional configuration of an ECU according to a fifth embodiment of the present invention.
FIG. 14 is a flowchart showing the operation of the return torque compensator according to the fifth embodiment of the present invention.
FIG. 15 is a diagram showing a time response of a handle angle in the fifth embodiment of the present invention.
FIG. 16 is a diagram showing a time response of a yaw rate in Embodiment 5 of the present invention.
FIG. 17 is a diagram showing a time response of a handle returning torque in the fifth embodiment of the present invention.
FIG. 18 is a block diagram showing a functional configuration of an ECU according to a sixth embodiment of the present invention.
FIG. 19 is a flowchart showing a part of the operation of the return torque compensator according to the sixth embodiment of the present invention.
FIG. 20 is a block diagram showing a functional configuration of an ECU according to a seventh embodiment of the present invention.
FIG. 21 is a flowchart showing a part of the operation of the return torque compensator according to the seventh embodiment of the present invention.
FIG. 22 is a block diagram showing a functional configuration of an ECU according to an eighth embodiment of the present invention.
FIG. 23 is a flowchart showing a part of the operation of the return torque compensator according to the eighth embodiment of the present invention.
FIG. 24 is a schematic configuration diagram of a conventional electric power steering control device.
FIG. 25 is a diagram showing a functional configuration of control means for controlling an electric motor in a conventional electric power steering control device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 Steering handle, 103 Torque sensor, 105 Electric motor, 107 Steering angle sensor, 111 ECU, 121 Steering torque controller, 123 Return torque compensator, 125 Damping compensator, 127 Inertia compensator, 129 Vehicle speed detector, 131 Steering torque detection , 133 steering shaft reaction force torque detector, 135 steering wheel angle detector, 137 motor speed detector, 139 motor acceleration detector, 141 adder, 143 subtractor, 145 motor driver, 147 motor current detector, 149 road surface Reaction force torque detector, 151 yaw rate detector, 153 yaw rate phase detector.

Claims (9)

A steering angle sensor for detecting a steering angle representing a rotation angle from a neutral position of the steering wheel;
A steering shaft reaction force torque sensor for detecting a reaction force torque of the steering system;
A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the return direction of the steering wheel by multiplying the steering angle detected by the steering angle sensor with a gain;
A control unit for controlling the gain so as to reduce the superimposed reaction force torque when the reaction force torque of the steering system is large, and to increase the superimposed reaction force torque when the reaction force torque of the steering system is small;
An electric power steering control device comprising: A steering angle sensor for detecting a steering angle representing a rotation angle from a neutral position of the steering wheel;
A road surface reaction force torque determining section for determining the road surface reaction torque of a road surface on which the vehicle travels,
A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the return direction of the steering wheel by multiplying the steering angle detected by the steering angle sensor with a gain;
A controller that controls the gain so as to reduce the superimposed reaction force torque when the road surface reaction torque is large, and to increase the superimposed reaction force torque when the road surface reaction torque is small;
An electric power steering control device comprising: A steering shaft reaction force torque sensor for detecting a reaction force torque of the steering system;
A road surface reaction force torque determining unit for obtaining a road surface reaction force torque of a road surface on which the vehicle travels, which is a state quantity obtained by subtracting the friction term from the steering shaft reaction force torque;
A superimposed reaction force torque calculating unit that calculates a superimposed reaction force torque in the return direction of the steering wheel by multiplying the road surface reaction force torque obtained by the road surface reaction force torque determining unit by a gain;
A control unit for controlling the gain so as to reduce the superimposed reaction force torque when the reaction force torque of the steering system is large, and to increase the superimposed reaction force torque when the reaction force torque of the steering system is small;
An electric power steering control device comprising: A road surface reaction force torque determining section for determining the road surface reaction torque of a road surface on which the vehicle travels,
A superimposed reaction force torque calculating unit that calculates a superimposed reaction force torque in the return direction of the steering wheel by multiplying the road surface reaction force torque obtained by the road surface reaction force torque determining unit by a gain;
When the road surface reaction torque, which is a state quantity obtained by subtracting the friction term from the steering shaft reaction force torque, is large, that is, when the steering shaft reaction force torque is large, the superimposed reaction force torque is reduced and the road surface reaction torque is small. A control unit for controlling the gain so as to increase the superimposed reaction torque when the steering shaft reaction torque is small,
An electric power steering control device comprising: A steering shaft reaction force torque sensor for detecting a reaction force torque of the steering system;
A state quantity sensor for detecting a state quantity of any of the yaw rate, lateral acceleration, and sideslip angle of the vehicle;
A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the return direction of the steering wheel by multiplying a gain by one of the state quantities of the vehicle yaw rate, lateral acceleration, and side slip angle detected by the state quantity sensor; ,
A control unit for controlling the gain so as to reduce the superimposed reaction force torque when the reaction force torque of the steering system is large, and to increase the superimposed reaction force torque when the reaction force torque of the steering system is small;
An electric power steering control device comprising: A state quantity sensor for detecting a state quantity of any of the yaw rate, lateral acceleration, and sideslip angle of the vehicle;
A road surface reaction torque determining unit that determines a road surface reaction torque of a road surface on which the vehicle travels;
A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the return direction of the steering wheel by multiplying a gain by one of the state quantities of the vehicle yaw rate, lateral acceleration, and side slip angle detected by the state quantity sensor; ,
A controller that controls the gain so as to reduce the superimposed reaction force torque when the road surface reaction torque is large, and to increase the superimposed reaction force torque when the road surface reaction torque is small;
An electric power steering control device comprising: A steering angle sensor for detecting a steering angle representing a rotation angle from a neutral position of the steering wheel;
A motor current detector for detecting a motor current supplied to an electric motor for power steering connected to a steering system;
A steering torque sensor for detecting torque when the driver of the car steers,
A steering shaft reaction force torque calculator that estimates a reaction torque of a steering system from the motor current detected by the motor current detector and the steering torque detected by the steering torque sensor;
A superimposed reaction force torque calculation unit for calculating a superimposed reaction force torque in the return direction of the steering wheel by multiplying the steering angle detected by the steering angle sensor with a gain;
A control unit for controlling the gain so as to reduce the superimposed reaction force torque when the reaction force torque of the steering system is large, and to increase the superimposed reaction force torque when the reaction force torque of the steering system is small;
An electric power steering control device comprising: The reaction torque Ttran of the steering system is expressed by the following equation:
Ttran = Thdl + Tassist−J · dw / dt
Here, Thdl is the steering torque, Tassist is the assist torque by the motor, J · dw / dt is the inertia torque of the motor,
8. The electric power steering control device according to claim 7, wherein   7. The electric power steering control device according to claim 2, wherein the road surface reaction torque is obtained by subtracting the friction torque of the steering system from the reaction torque of the steering system. .

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